|Scientific Name:||Montipora dilatata Studer, 1901|
|Red List Category & Criteria:||Endangered B2ac(iii) ver 3.1|
|Assessor(s):||DeVantier, L., Hodgson, G., Huang, D., Johan, O., Licuanan, A., Obura, D., Sheppard, C., Syahrir, M. & Turak, E.|
|Reviewer(s):||Livingstone, S., Polidoro, B. & Smith, J. (Global Marine Species Assessment)|
The population of this species on Oahu declined drastically to only two known remaining colonies after a bleaching event in 1996. Colonies have since increased to approximately ten. On the northwestern Hawaiian Islands, it remains common in a few areas, despite bleaching events in 2002 (Aeby pers. comm.). This species appears more resistant to bleaching than other Montipora species, but the chances of serious decline due to future bleaching events are very high. This species is listed as Endangered under B criterion as its area of occupancy is less than a total of 500 km² and exists in less than five locations (as dictated by threat). The population has experienced serious fluctuations over the last 20 years due to climate change related events. It will be important to reassess this species in 10 years time because of predicted continued threats from climate change and ocean acidification.
|Range Description:||In the Indo-West Pacific, this species is found in the Hawaiian Islands, where it is known only from Kaneohe Bay on Oahu in the main island group, and in the Northwestern Hawaiian Islands it is known in 2004 from four islands: Midway (two sites); Kure (two sites), Pearl and Hermes (two sites) and Lisianski (one site). The records from the Northwestern islands had previously been recorded as Montipora turgescens. However, inspection of photographs provided by Aeby (pers. comm.) indicate that the species in question is likely to be M. diiatata. Corals possibly belonging to this species have been reported from one location on Palmyra in the Line Islands (Maragos and Obura), and this requires confirmation.|
Native:United States (Hawaiian Is.)
|FAO Marine Fishing Areas:|
Pacific – eastern central; Pacific – northwest
|Range Map:||Click here to open the map viewer and explore range.|
|Population:||The population on Oahu declined drastically to two known remaining colonies after a bleaching event in 1996, which have since increased to approximately ten. On the northwestern Hawaiian Islands, it remains common in a few locations, despite bleaching events in 2002 (Aeby pers. comm.).|
The age of first maturity of most reef building corals is typically three to eight years (Wallace 1999) and therefore we assume that average age of mature individuals is greater than eight years. Furthermore, based on average sizes and growth rates, we assume that average generation length is 10 years, unless otherwise stated. Total longevity is not known, but likely to be more than ten years. Therefore any population decline rates for the Red List assessment are measured over at least 30 years. See the Supplementary Material for further details on generation length estimates.
|Current Population Trend:||Decreasing|
|Habitat and Ecology:||It occurs in shallow back reef environments with strong surge. This species is found to at least 10 m.|
|Generation Length (years):||10|
The bleaching of coral reefs, which has become increasingly frequent since the 1970s, is related to the ongoing rise in ocean in temperatures as a result of global climate change. Bleaching events, leading to coral mortality, are predicted to become more frequent and severe.
Acanthaster planci, the crown-of-thorns starfish, has been observed preferentially preying upon members of this genus (Colgan 1987). Crown-of-thorns starfish (COTS) (Acanthaster planci) are found throughout the Pacific and Indian Oceans, and the Red Sea. These starfish are voracious predators of reef-building corals, with a preference for branching and tabular corals such as Acropora species. Populations of the crown-of-thorns starfish have greatly increased since the 1970s and have been known to wipe out large areas of coral reef habitat. Increased breakouts of COTS has become a major threat to some species, and have contributed to the overall decline and reef destruction in the Indo-Pacific region. The effects of such an outbreak include the reduction of abundance and surface cover of living coral, reduction of species diversity and composition, and overall reduction in habitat area.
In the northwest Hawaiian islands this species was more resistant to bleaching than M. capitata, which bleached and died. Montipora dilatata bleached and recovered (Aeby pers. comm.). It is also less susceptible to disease. The Oahu population crashed to near zero due to bleaching, and has had a very slow recovery.
In general, the major threat to corals is global climate change, in particular, temperature extremes leading to bleaching and increased susceptibility to disease, increased severity of ENSO events and storms, and ocean acidification.
Coral disease has emerged as a serious threat to coral reefs worldwide and a major cause of reef deterioration (Weil et al. 2006). The numbers of diseases and coral species affected, as well as the distribution of diseases have all increased dramatically within the last decade (Porter et al. 2001, Green and Bruckner 2000, Sutherland et al. 2004, Weil 2004). Coral disease epizootics have resulted in significant losses of coral cover and were implicated in the dramatic decline of acroporids in the Florida Keys (Aronson and Precht 2001, Porter et al. 2001, Patterson et al. 2002). In the Indo-Pacific, disease is also on the rise with disease outbreaks recently reported from the Great Barrier Reef (Willis et al. 2004), Marshall Islands (Jacobson 2006) and the northwestern Hawaiian Islands (Aeby 2006). Increased coral disease levels on the GBR were correlated with increased ocean temperatures (Willis et al. 2007) supporting the prediction that disease levels will be increasing with higher sea surface temperatures. Escalating anthropogenic stressors combined with the threats associated with global climate change of increases in coral disease, frequency and duration of coral bleaching and ocean acidification place coral reefs in the Indo-Pacific at high risk of collapse.
Localized threats to corals include fisheries, human development (industry, settlement, tourism, and transportation), changes in native species dynamics (competitors, predators, pathogens and parasites), invasive species (competitors, predators, pathogens and parasites), dynamite fishing, chemical fishing, pollution from agriculture and industry, domestic pollution, sedimentation, and human recreation and tourism activities.
The severity of these combined threats to the global population of each individual species is not known.
Several colonies are now growing ex situ. Research on the resistance of M. capitata to bleaching stress could also be extended to this species.
All corals are listed on CITES Appendix II. Parts of the species’ range fall within Marine Protected Areas.
Recommended measures for conserving this species include research in taxonomy, population, abundance and trends, ecology and habitat status, threats and resilience to threats, restoration action; identification, establishment and management of new protected areas; expansion of protected areas; recovery management; and disease, pathogen and parasite management. Artificial propagation and techniques such as cryo-preservation of gametes may become important for conserving coral biodiversity.
Having timely access to national-level trade data for CITES analysis reports would be valuable for monitoring trends this species. The species is targeted by collectors for the aquarium trade and fisheries management is required for the species, e.g., MPAs, quotas, size limits, etc. Consideration of the suitability of species for aquaria should also be included as part of fisheries management, and population surveys should be carried out to monitor the effects of harvesting. Recommended conservation measures include population surveys to monitor the effects of collecting for the aquarium trade, especially in Indonesia.
|Citation:||DeVantier, L., Hodgson, G., Huang, D., Johan, O., Licuanan, A., Obura, D., Sheppard, C., Syahrir, M. & Turak, E. 2008. Montipora dilatata. The IUCN Red List of Threatened Species 2008: e.T133170A3612492.Downloaded on 12 December 2017.|
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